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vdso: Introduce aux_clock_resolution_ns() 

Move the constant resolution to a shared header,
so the vDSO can use it and return it without going through a syscall.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250701-vdso-auxclock-v1-10-df7d9f87b9b8@linutronix.de
This commit is contained in:
Thomas Weißschuh 2025-07-01 10:58:04 +02:00 committed by Thomas Gleixner
parent 562f03ed96
commit 9b7fc3f145
2 changed files with 17 additions and 2 deletions
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13
include/vdso/auxclock.h Normal file
View File

@ -0,0 +1,13 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _VDSO_AUXCLOCK_H
#define _VDSO_AUXCLOCK_H
#include <uapi/linux/time.h>
#include <uapi/linux/types.h>
static __always_inline u64 aux_clock_resolution_ns(void)
{
return 1;
}
#endif /* _VDSO_AUXCLOCK_H */

6
kernel/time/timekeeping.c
View File

@ -26,6 +26,8 @@
#include <linux/audit.h>
#include <linux/random.h>
#include <vdso/auxclock.h>
#include "tick-internal.h"
#include "ntp_internal.h"
#include "timekeeping_internal.h"
@ -2876,8 +2878,8 @@ static int aux_get_res(clockid_t id, struct timespec64 *tp)
if (!clockid_aux_valid(id))
return -ENODEV;
tp->tv_sec = 0;
tp->tv_nsec = 1;
tp->tv_sec = aux_clock_resolution_ns() / NSEC_PER_SEC;
tp->tv_nsec = aux_clock_resolution_ns() % NSEC_PER_SEC;
return 0;
}